The background of the present invention is not amenable to any brief summary, since any discussion of this kind would depend on whatever starting point might be chosen. Containers of various forms are known having a transparent cover for displaying a contained article. Flaps of "lenticular" outline have been used to bow the walls of the container away from each other and to form end closures of the container. The term "lenticular" is used here to refer to a shape formed by two intersecting arcs that bow away from each other (like the cross-section of a double convex lens) and equivalent shapes.